GCN Circular 29281
Subject
GRB 201227A: continued Chilescope confirmation of variability of possible optical counterpart, redshift estimating
Event
Date
2021-01-08T16:20:33Z (5 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), A. Pozanenko (IKI), P. Minaev (IKI), M. Krugov (FAI)
report on behalf of GRB IKI FuN collaboration:
We continued observations of the field of XRT #2 sources (D'Elia et al.,
GCN 29202) (hereafter X2) found in IPN localization area (Svinkin et
al., GCN 29182) of GRB 201227A (Ursi et al., GCN 29179; Xiao et al., GCN
29187; Svinkin et al., GCN 29196; Lesage et al., GCN 29206; Marisaldi et
al., GCN 29276) with Chilescope RC-1000 on 2021-01-01 and 2021-01-08 in
r'-filter.
The X2_O2 object found in previous observation on 2020-12-29 at r'(AB)=
20.5 (Belkin et al., GCN 29208; see also Izzo et al., GCN 29207) is not
detected on 2021-01-01 with an upper limit of r'(AB) > 20.6 and barely
detected on 2021-01-08 at r'(AB)=22.6. Now we confirm the variability of
the object of X2_O2 and suggest the optical object X2_02 could be a
counterpart of GRB 201227A. In the last image on 2021-01-08, the object
X2_O2 could be the host galaxy. A finding chart of the X2_O2 can be found in
http://grb.rssi.ru/GRB201227A/GRB201227A_r_FC_201229_2100108.png
Preliminary photometry of the X2_O2 is following
Date UT start t-T0 Filter Exp. OT(AB) Err. UL(AB) FWHM
(mid, days) (s)
2021-01-01 05:57:21 4.63072 r' 5*600 n/d n/d 20.6 1.5"
2021-01-08 04:15:45 11.5636 r' 3*1200 22.6 0.4 22.5 1.4"
The photometry is based on nearby stars from the APASS_DR8
RA DEC r
11:19:31.40904 -73:35:47.6880 14.090
11:19:44.89128 -73:34:49.6092 15.180
11:19:36.65304 -73:36:30.2112 15.307
In addition we investigated a position of the GRB 201227A on the EHD
diagram (see Minaev et al., MNRAS, 492, 1919, 2020). The position of
GRB 201227A based on Konus-Wind data (Svinkin et al., GCN Circ. 29196)
can be found in
http://grb.rssi.ru/GRB201227A/GRB201227A_EH_T90i.png
We can exclude the GRB 201227A as a giant flare event of SGR since there
is no nearby galaxies in the IPN error box. We can identify the GRB
201227A as short GRB at a redshift of z > 0.05.